Abstract
We consider the two-Higgs-doublet model as a framework in which to evaluate the viability of scenarios in which the sign of the coupling of the observed Higgs boson to down-type fermions (in particular, -quark pairs) is opposite to that of the Standard Model (SM), while at the same time all other tree-level couplings are close to the SM values. We show that, whereas such a scenario is consistent with current LHC observations, both future running at the LHC and a future linear collider could determine the sign of the Higgs coupling to -quark pairs. Discrimination is possible for two reasons. First, the interference between the -quark and the -quark loop contributions to the coupling changes sign. Second, the charged-Higgs loop contribution to the coupling is large and fairly constant up to the largest charged-Higgs mass allowed by tree-level unitarity bounds when the -quark Yukawa coupling has the opposite sign from that of the SM (the change in sign of the interference terms between the -quark loop and the and loops having negligible impact).
5 More- Received 26 March 2014
DOI:https://doi.org/10.1103/PhysRevD.89.115003
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